Electromagnetically-operated switch.



E. T. R. MURRAY 6L G. F. SHOTTER. ELECTROMAGNETICALLY OPERATED DEVICE.

vAPPLICATION FILED MAR.23,1916.

PatentedApr.-9,1918.

Figi.'

UNTD FFE.

ETHELBERT THOMAS RU'rHvEN MURRAY, er nsnnn'rr, AND GEORGE FREDERICK y sHo'rirEn, or srnnarrrnia, LONDON, ENGLAND.

ELECTROMAGNETICLLY-OPERATED DEVICE.

Application filed March 23, 1916.

To all whom t may concern:

Be it known that we, ETHELBERT THOMAS RUTHVEN MURRAY and GEORGE FREDERICK SHOTTER, subjects of the King of Great Britain, residing at, respectively, Radlett, Hertfordshire, and Streatham, London, England, have invented certain new and useful Improvements in and Relating to Electromagnetically-Operated Devices, of which the following is a specitication.

This invention relates to electro-magnetically operated devices such as electro-magnetic relays of the kind in which the current necessary to operate the device can be varied by varying the length of the air-gap separating the fixed and movable magnetic elements of the device.

Apparatus of the above description as hitherto constructed is open to the disadvantage that the variation in the current required to effect the attractive movement of the armature or movable element of the device is not directly or approximately directly proportional to the length of the air-gap separating the iixed and movable elements when the latter is in its unattracted position. In general the longer the initial length of the air-gap the greater the increase of current required toeffect the movement of the armature for a given increase in the length of the air-gap. It for instance, with an air-gap of l0 mm. an increase of current of one ampere is required to cause the armature to move when the airgap is increased by l min. the same increase of air-gap when the latter is 20 mm. in length will require an increase in current of say four amperes to operate the device.

Owing to the nature of the variation above indicated it has not been possible to construct a device of this character in which a given variation in the length of the airgap shall correspond to a given increase in operating current for all lengths of air-gap on a considerable range and thus obtain a uniform scale for the adjustment of the device.

It has also not been practicable as may be required in some cases to cause the scale of adjustment to be more open throughout a certain desiredl portion of its range than in the remaining portion.

The present invention has for its object to overcome this difficulty and to construct Specification of Letters Patent.

Patented Apr. 9, 1918.

serial No. 86,322.

an improved form of electro-magnetically operated device in which any desired relation between the variation in the length of the air-gap and the consequent variation in the current required to operate the device can be obtained, this relation being either uniform throughout the whole range of the device or different at different portions thereof.

A further advantage of the improved construction is its extreme immunity from interference by external magnetic fields.

According to our invention, the exciting coil of the apparatus is arranged to surround a pivoted or otherwise movable core or armature in such a manner as to permit iree movement of the latter within the coil in a direction substantially transverse to the axis of the coil in a plane containing the said axis, and a fixed or adjustable yoke, as may be expedient, is placed in the same plane as the movement of the pivoted or otherwise movable core which is provided with arrangement :t'or adj ustably varying` the air-gap separating the core from the yoke so as to enable the current necessary to operate the apparatus to be adjusted.

it so desired, a modification of the laws governing the above combination can be produced by inducing, from the same source, a. second flux in a` secondary ixed or adjustable yoke placed within or without the coil in such a manner that it exerts a repulsive or attractive action as required upon the movable armature, in addition to the attraction exerted between that armature and the main yoke.

rilhe invention is illustrated in the accompanying drawings, in which,

Figure l is a view in side elevation of the electro-magnetic relay embodying the invention.

Figs. 2 and 3 being views in end elevation and sectional Side elevation respectively or the same device.

Referring now to the drawing, it will be seen that the relay comprises a core 0r armature l pivotally mounted as indicated at 2 to the :frame 3 ot the device. rThe armature l which is shown in its attracted or closed position in `the drawing is provided with a counterweight l adapted to counterbalance the weight of the opposite end ot the armature l to that to which it is secured.

The armature 1 constitutes one portion of a magnetic circuit, the other portion of which is constituted by a fixed yoke 5.

The exciting coil or solenoid of the relay is indicated at 6 and is, as will be seen from the drawing, ot' special form, being wedge shaped in side elevation and surrounding the movable aimature 1 in such a manner as -to permit free oscillation or rocking movement of the latter within the energizing coil'6. The exciting coil is preferably constructed by beingI wound upon a suitable 'former and subsequently provided with end plates 7 mounted on the frame 3 by means of which the coil is secured to the fixed yoke 5 by means of screws S. The two ends of the exciting coil'6 are connected to suitable terminals 9 mounted on the frame 3 which are connected to the controlling circuit of the relay in the usual manner.

The relay illustrated in the drawing is adapted when energized to operate a releasing mechanism for a mechanically actuated device not shown, and for this purpose a resilient Sti-ip indicated at 10 is provided, one end of which is rigidly secured to a pillar 11 mounted on the trame 3, the opposite end of the strip l0 carrying a releasing catch 12. To an intermediate point in the resilient strip 10 is attached a striker pin 13 which projects downward through a guide 14 secured to the frame 3 in vsuoli a manner that the lower end of the striker pin 13 is engaged by the armature 1 when the latter is'in its fully attracted position as shown in the'drawing.

The armature 1-is so balanced by its counter-weight 4 as to fall away from the striker pin 13 when the relay is de'e'nergized .to a positionV determined by means of an adjustable set screw 15 forming a stop defining the extent of the downward travel of the armature 1.

The r*operation ofthe relay is as follows- Vhen the coil 6 of the relay is denergized the armature 1 occupies a position dependent uponthe adjustment of the set screw 15 being Separated from the fixed yoke 5 by an air-gap dependent upon the adjustment of the set screw. iVhen the coil 6 is energized and traversed by a current of suitable strength, thel armature 1 is attracted and moves into the position shown in the drawing, thereby coming into contact with the end of the striker pin 13, and raising the latter and the releasing catch 12. VOwing to the peculiar form of the exciting coil' 6, for instance, the energizing current required to raise the armature to its attracted position may be arranged to be directly proportional to the length of the air-gap between the ixed yoke 5y and the armature 1 when the latter is in its unattracted position. rThis characteristic is dependent upon the relative position of the energizing coil 6 'and 0i the fixed yoke 5 and the movable armature 1, and the form of coil illustrated enables the characteristic above mentioned by wa of example, to be readily obtained, as 1t wi l be seen that the relative positions of the fixed yoke 5 and the exciting coil 6 are not affected by any adjustment of the set screw 15, whereas the movable core or armature 1 is, for any adjustment of this Set screw, surrounded equally by the exciting coil 6.

The effect obtained by this construction may be modified as required by the provision of the Strip or bar of magnetic material indicated at 16, this bar lying along the lower face ofy the interior of the excitin coil 6 and being-supported by a slotted pilar 1T mounted on the frame 3, thus enabling the action of the bar 16 to be adjusted by sliding the bar to a greater or less extent within the exciting coil 6.

As will be readily understood the current traversing the coil 6 will cause the bar 16 to become magnetized in the same direction as the movable armature 1 so that the latter is repelled upward when the 'relay is energized and the attractive forces exerted on the armature 'are thereby assisted particularly for large air gaps with a corresponding modication of the characteristic of the device.

1t will be seen from the above description that the increase of current required (necessary to cause the armature to he attracted) for a given increase of air-gap, can be arranged to be uniform throughout the range of the device or to be diiferentat different portionsI thereof as `desired by modifying the form of the exciting coil with or without the additional iniiuence of the repulsive action of the -bar or strip of magnetic material.

rl`he inventionis particularly useful in con# nectioii with current limiters of the adjustable type, the mechanism shown in the drawingsA with its resilient strip 10 and releasing catch 12 beingdesign'ed ior use with an apparatus of this-character, but it will be understood that any other form of mechanism may be arranged to be operated by the arma;- ture 1, such for instance as a switch mechanism,- tlie contacts of which are closed or opened when the armature is in its 'attracted position. Variation in this respect as well as in the mechanical construction and rela.- tive disposition of theparts of the relay may obviously be made without departing from the scope of the invention.

That we claimis: j

1. An electro-magnetically operated control mechanism comprising an exciting coil formed of wedge-shaped section in one plane along its axis, 'an armature and means for pivotally supporting th'esame in a position passing through the coil, and so that its end distant from the pivot is at the wider end of the coil, a yoke piece external to the coil and having its ends in positions to coperat with said armature on the passage of electric current through the coil, and an adjustable stop adapted to limit the movement of said armature away from said yoke piece.

2. An electro-magnetically operated control mechanism comprising an exciting coil of oblong transverse section and wedgeshaped longitudinal section, an armature passing through said coil, a pivotal support for said armature adjacent the smaller end of the coil, the plane of pivoting movement of said armature being parallel to the axis of the coil, a yoke piece external to the coil and having its ends in positions to coperate with said armature on the passage of electric current through the coil, and an adjustable stop adapted to limit the movement of said armature away from said yoke piece.

3. An electro-magnetically operated control mechanism comprising an exciting coil, an armature passing therethrough7 a pivotal support for said armature adj acent one end ot' said coil, a yoke pie-ce external to said coil and having` its endsin positions to cooperate with said armature on the passage of electric current through the coil, a bar of magnetizable material located adjacent the armature in such position that said bar will be magnet-ized and will exert a repellant action on saidarmature when electric current tlows in said coil, said bar being at the opposite side of said armature to said yoke piece, and a stop adapted to limit the free movement of said armature away from said yoke piece. Y

l. An electro-magnetically operated con trol mechanism comprising an exciting coil wider in its opening at one end than at the other, an armature and a pivotal support 'for the same adjacent the narrower end ot' said coil, a yoke piece external to said coil and having its ends in positions adapted to co- Copies of this patent may be obtained for operate with said armature on the passage of electric current through said coil, a bar of megnetizable material and means for supporting` the same in an adjustable manner in position adjacent said armature but on the opposite side thereof with respect to the yoke piece, whereby said bar is enabled to be magnetized by said coil and to serve to repel the armature toward the yoke piece, and a stop adapted to limit the free movement of said armature away from said yoke piece.

5. An electro-magnetically operated control mechanism comprising a coil wedgeshaped in section in one longitudinal plane, an armature passing through the coil, a pivotal support for said armature adjacent one end of the coil and adapted to permit pivotal movement thereof in said longitudinal plane, a yoke piece external to said coil, and adapted to cooperate with said armature on the passage ot electric current through said coil, a bar of niagnetizable material and a support for the same adapted to hold it in a position lying along the inside of the coil at the side of the armature opposite to the yoke piece, and adapted to permit the bar to be slid longitudinally so as to project to a greater or less extent into the coil, whereby the repellant action of said magnetizable bar on said armature may be varied, and an adjustable stop adapted to limit the movement of said armature away from said yoke piece.

In testimony whereof we have hereunto set our hands in presence of two subscribing witnesses.

ETHELBER'I THMAS RUTHVEN MURRAY. GEORGE FREDERICK SHO'lTER.

Witnesses FRANK J. AMES, HERBERT D. JAMESON.

five cents each, b addressnthe Commissioner of Patents,

Washington, D. C. 

